Under the system, migrants seeking asylum in the United States would be returned to the last country they transited while their application is being processed. The Mexican foreign ministry's position:
A Safe Third Country Agreement would mean that all migrants, all of them, from anywhere in the world, who travel through Mexico to request asylum would be returned to our country and their only option would be to request asylum in Mexico. That is why we will not accept this type of treaty.
As we said on Friday, we reiterate that under no circumstances has Mexico accepted, either de jure or de facto, the status of Safe Third Country for people entering our territory seeking access to the United States. Mexico has not signed, nor will it agree to sign, a treaty that would put it in that situation.
https://www.gob.mx/sre/en/articulos/rem ... 1?idiom=en
In other words, Mexico sympathizes with the plight of migrants, as long as it doesn't have to do anything more than express sympathy. If it actually has to spend money ...
¡Adios, muchachos!